Allowance for Loan and Lease Losses - Components of Allowance for Loan and Lease Losses by Impairment Methodology (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for loan and lease losses by impairment methodology:
Collectively evaluated	$ 4,744	$ 4,056
Asset-specific	349	300
Total allowance for loan and lease losses	$ 5,130	$ 4,383
Loans held for investment by impairment methodology:
Allowance as a percentage of period-end loans held for investment	2.23%	2.10%
Collectively evaluated	$ 208,084	$ 183,107
Asset-specific	2,249	1,709
Loans held for investment	229,851	208,316	$ 197,199
Credit Card Portfolio Segment [Member]
Allowance for loan and lease losses by impairment methodology:
Collectively evaluated	3,445	2,985
Asset-specific	209	219
Total allowance for loan and lease losses	$ 3,654	$ 3,204	3,214
Loans held for investment by impairment methodology:
Allowance as a percentage of period-end loans held for investment	3.80%	3.73%
Collectively evaluated	$ 95,459	$ 85,161
Asset-specific	666	692
Loans held for investment	96,125	85,876
Consumer Portfolio Segment [Member]
Allowance for loan and lease losses by impairment methodology:
Collectively evaluated	778	710
Asset-specific	54	42
Total allowance for loan and lease losses	$ 868	$ 779	752
Loans held for investment by impairment methodology:
Allowance as a percentage of period-end loans held for investment	1.23%	1.09%
Collectively evaluated	$ 51,113	$ 47,507
Asset-specific	699	647
Loans held for investment	70,372	71,439
Commercial Banking
Allowance for loan and lease losses by impairment methodology:
Collectively evaluated	517	356
Asset-specific	86	39
Total allowance for loan and lease losses	$ 604	$ 395	338
Loans held for investment by impairment methodology:
Allowance as a percentage of period-end loans held for investment	0.95%	0.78%
Collectively evaluated	$ 61,424	$ 50,328
Asset-specific	884	370
Loans held for investment	63,266	50,890
Other
Allowance for loan and lease losses by impairment methodology:
Collectively evaluated	4	5
Asset-specific	0	0
Total allowance for loan and lease losses	$ 4	$ 5	$ 11
Loans held for investment by impairment methodology:
Allowance as a percentage of period-end loans held for investment	4.94%	4.68%
Collectively evaluated	$ 88	$ 111
Asset-specific	0	0
Loans held for investment	88	111
Receivables Acquired with Deteriorated Credit Quality [Member]
Allowance for loan and lease losses by impairment methodology:
Financing Receivable, Allowance for Credit Losses	37	27
Loans held for investment by impairment methodology:
Loans held for investment	19,518	23,500
Receivables Acquired with Deteriorated Credit Quality [Member] \| Credit Card Portfolio Segment [Member]
Allowance for loan and lease losses by impairment methodology:
Financing Receivable, Allowance for Credit Losses	0	0
Loans held for investment by impairment methodology:
Loans held for investment	0	23
Receivables Acquired with Deteriorated Credit Quality [Member] \| Consumer Portfolio Segment [Member]
Allowance for loan and lease losses by impairment methodology:
Financing Receivable, Allowance for Credit Losses	36	27
Loans held for investment by impairment methodology:
Loans held for investment	18,560	23,285
Receivables Acquired with Deteriorated Credit Quality [Member] \| Commercial Banking
Allowance for loan and lease losses by impairment methodology:
Financing Receivable, Allowance for Credit Losses	1	0
Loans held for investment by impairment methodology:
Loans held for investment	958	192
Receivables Acquired with Deteriorated Credit Quality [Member] \| Other
Allowance for loan and lease losses by impairment methodology:
Financing Receivable, Allowance for Credit Losses	0	0
Loans held for investment by impairment methodology:
Loans held for investment	0	$ 0
GE Healthcare [Member] \| Commercial Banking
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan and Lease Losses, Loans Acquired	$ 39

Financing Receivable, Allowance for Credit Losses, Percentage of Held for Investment Loans

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Held for investment loans by impairment methodology.

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Amount of addition to allowance reserve for credit loss arising from purchase of loan and lease portfolios.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(d))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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A valuation allowance for financing receivables that are expected to be uncollectible.

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The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The balance of financing receivables that were collectively evaluated for impairment.

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The balance of financing receivables that were individually evaluated for impairment.

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- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953423-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953423-111524

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(d))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (b)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 6
-Section L
-Subsection 1

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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

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-Name Accounting Standards Codification
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-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522

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